The bitbang spi driver currently only supports the MSB mode. This patch adds the possibility to clock the data in LSB mode.
Signed-off-by: Michael Grzeschik <[email protected]> --- drivers/spi/spi-bitbang-txrx.h | 98 +++++++++++++++++++++++++++++------------- drivers/spi/spi-bitbang.c | 3 +- 2 files changed, 71 insertions(+), 30 deletions(-) diff --git a/drivers/spi/spi-bitbang-txrx.h b/drivers/spi/spi-bitbang-txrx.h index b6e348d..7f9c020 100644 --- a/drivers/spi/spi-bitbang-txrx.h +++ b/drivers/spi/spi-bitbang-txrx.h @@ -49,22 +49,42 @@ bitbang_txrx_be_cpha0(struct spi_device *spi, { /* if (cpol == 0) this is SPI_MODE_0; else this is SPI_MODE_2 */ - /* clock starts at inactive polarity */ - for (word <<= (32 - bits); likely(bits); bits--) { - - /* setup MSB (to slave) on trailing edge */ - if ((flags & SPI_MASTER_NO_TX) == 0) - setmosi(spi, word & (1 << 31)); - spidelay(nsecs); /* T(setup) */ - - setsck(spi, !cpol); - spidelay(nsecs); - - /* sample MSB (from slave) on leading edge */ - if ((flags & SPI_MASTER_NO_RX) == 0) - word |= getmiso(spi); - setsck(spi, cpol); - word <<= 1; + if (spi->mode & SPI_LSB_FIRST) { + /* clock starts at inactive polarity */ + for (; likely(bits); bits--) { + + /* setup MSB (to slave) on trailing edge */ + if ((flags & SPI_MASTER_NO_TX) == 0) + setmosi(spi, word & 1); + spidelay(nsecs); /* T(setup) */ + + setsck(spi, !cpol); + spidelay(nsecs); + + /* sample LSB (from slave) on leading edge */ + if ((flags & SPI_MASTER_NO_RX) == 0) + word |= getmiso(spi); + setsck(spi, cpol); + word >>= 1; + } + } else { + /* clock starts at inactive polarity */ + for (word <<= (32 - bits); likely(bits); bits--) { + + /* setup MSB (to slave) on trailing edge */ + if ((flags & SPI_MASTER_NO_TX) == 0) + setmosi(spi, word & (1 << 31)); + spidelay(nsecs); /* T(setup) */ + + setsck(spi, !cpol); + spidelay(nsecs); + + /* sample MSB (from slave) on leading edge */ + if ((flags & SPI_MASTER_NO_RX) == 0) + word |= getmiso(spi); + setsck(spi, cpol); + word <<= 1; + } } return word; } @@ -76,22 +96,42 @@ bitbang_txrx_be_cpha1(struct spi_device *spi, { /* if (cpol == 0) this is SPI_MODE_1; else this is SPI_MODE_3 */ - /* clock starts at inactive polarity */ - for (word <<= (32 - bits); likely(bits); bits--) { + if (spi->mode & SPI_LSB_FIRST) { + /* clock starts at inactive polarity */ + for (; likely(bits); bits--) { + + /* setup MSB (to slave) on leading edge */ + setsck(spi, !cpol); + if ((flags & SPI_MASTER_NO_TX) == 0) + setmosi(spi, word & 1); + spidelay(nsecs); /* T(setup) */ + + setsck(spi, cpol); + spidelay(nsecs); + + /* sample MSB (from slave) on trailing edge */ + if ((flags & SPI_MASTER_NO_RX) == 0) + word |= getmiso(spi); + word >>= 1; + } + } else { + /* clock starts at inactive polarity */ + for (word <<= (32 - bits); likely(bits); bits--) { - /* setup MSB (to slave) on leading edge */ - setsck(spi, !cpol); - if ((flags & SPI_MASTER_NO_TX) == 0) - setmosi(spi, word & (1 << 31)); - spidelay(nsecs); /* T(setup) */ + /* setup MSB (to slave) on leading edge */ + setsck(spi, !cpol); + if ((flags & SPI_MASTER_NO_TX) == 0) + setmosi(spi, word & (1 << 31)); + spidelay(nsecs); /* T(setup) */ - setsck(spi, cpol); - spidelay(nsecs); + setsck(spi, cpol); + spidelay(nsecs); - /* sample MSB (from slave) on trailing edge */ - if ((flags & SPI_MASTER_NO_RX) == 0) - word |= getmiso(spi); - word <<= 1; + /* sample MSB (from slave) on trailing edge */ + if ((flags & SPI_MASTER_NO_RX) == 0) + word |= getmiso(spi); + word <<= 1; + } } return word; } diff --git a/drivers/spi/spi-bitbang.c b/drivers/spi/spi-bitbang.c index bd222f6..3624f96 100644 --- a/drivers/spi/spi-bitbang.c +++ b/drivers/spi/spi-bitbang.c @@ -432,7 +432,8 @@ int spi_bitbang_start(struct spi_bitbang *bitbang) spin_lock_init(&bitbang->lock); if (!master->mode_bits) - master->mode_bits = SPI_CPOL | SPI_CPHA | bitbang->flags; + master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_LSB_FIRST + | bitbang->flags; if (master->transfer || master->transfer_one_message) return -EINVAL; -- 1.9.0 -- To unsubscribe from this list: send the line "unsubscribe linux-spi" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
